Liquid crystal display device has advantages of light weight, compact, low power consumption, so it is widely used in modern information equipment. As the liquid crystal display device (LCD for short) doesn't have a characteristic of self-luminescence, it depends on a backlight for offering enough and uniformly distributed light sources to achieve the display function, so the quality of backlight module affects the quality of the LCD directly. Under the development of the liquid crystal display device is trending towards a narrow frame, the backlight module should both meet the appearance requirement of narrow frame and protect the LCD efficiently while offering light source. The four corners of the LCD are most likely to be damaged when being subjected to external force, so it is extremely important to protect the corners of the LCD.
FIG. 1 is a simplified structural schematic view of a backlight module known by the present inventors. Referring to FIG. 1, in the design of the backlight module, the material of sealing frame 1 is hard plastic. Referring to FIG. 2, the sealing frame 1 is formed in a single piece by a molding process.
In order to protect the four corners of the display panel 2, the corresponding corners of the sealing frame 1 in backlight module are designed as escape angle portions 5, referring to FIG. 3. FIG. 3 is an enlarged view of area A shown in FIG. 1. The escape angle portion 5 can prevent damage to the liquid crystal display panel 2 due to the stress generated between the corners of the display panel 2 and the sealing frame 1 made of hard plastic material under external force.
With the development of the narrow frame of the display device, the corresponding backlight module also demands for a narrower and narrower frame. When the wall thickness of the sealing frame 1 is too thin, the escape angle portion 5 cannot be made at the corners, since the escape angle portion 5 cannot be made by the injection molding process if the wall thickness of the sealing frame 1 is too thin. Under this condition, it is necessary to increase the thickness of the wall of the sealing frame 1 accordingly to ensure the molding design of the escape angle portion 5, which is in conflict with narrow frame design. Therefore the escape angle portion 5 is omitted consequently, which will increase the risk of damage of corner parts of the display panel 2.